1. Field of the Invention
The present invention relates to a fixing structure for an axle tube of a motor, wherein the axle tube can be fixed easily and a longitudinal central axis of the axle tube is orthogonal to a plane on which the support member for the axle tube locates, thereby providing stable and non-tilt rotation for the rotor.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional motor comprising a metal plate 90 that is punched to form a tube 901 around which a circuit board 91 and a stator bobbin 92 are mounted. An axle tube 93 is extended through the circuit board 91 and the stator bobbin 92 and mounted into the tube 901. The axle tube 93 includes a bearing 931 mounted therein for rotatably holding a shaft 941 of a rotor 94. The shaft 941 extending through the bearing 931 is retained in place by a retaining element, such as a C-clip 95. A distal end of the shaft 94 rests on a bottom wall of an end cap 96 secured in an end of the axle tube 93.
In such a conventional motor, the tube 901 must be formed by punching. In addition, the tube 901 must be in an extremely tight engagement with the axle tube 93 by powerful punching. This requires highly precise punching device 2 to accomplish the extremely tight engagement between the axle tube 93 and the tube 901 after they are engaged. If the tube 901 is not in extremely tight engagement with the axle tube 93, the shaft 941 of the rotor 94 supported in the axle tube 93 will wobble while rotating. In addition, the longitudinal axis of the axle tube 93 must be exactly orthogonal to a plane on which the metal plate 90 locates. Otherwise, the rotor 94 cannot rotate in a stable and balanced state and noise is generated and the longevity thereof is shortened. In a case that the tube 901 is made from plastic material, the axle tube 93 and the tube 901 may be loosened from each other or even damaged after they are punched, as the axle tube 93 and the tube 901 are made from different material and thus have different heat-expansion coefficients. In addition, the axle tube 93 and the tube 901 are engaged in a way that is difficult to keep the rotor 94 rotating in a stable state after the rotor 94 is mounted in the bearing 931 in the axle tube 93.
It is the primary object of the present invention to provide a fixing structure for an axle tube of a motor, wherein the axle tube can be fixed easily and a longitudinal central axis of the axle tube is orthogonal to a plane on which the support member for the axle tube locates.
A fixing structure for an axle tube of a motor comprises a support member including an assembly hole through which a relatively smaller outer diameter portion of an outer periphery of an end cap extends. The end cap includes a relatively larger outer diameter portion having an end face abutting against a lower side of the support member. The relatively smaller outer diameter portion of the end cap is extended through the assembly hole of the axle tube and engaged with a relatively larger inner diameter portion of an axle tube that further includes a relatively smaller inner diameter portion in which a bearing is secured. An end face of the axle tube abuts against an upper side of the support member while the relatively larger outer diameter portion of the end cap abuts against the lower side of the support member, thereby sandwiching the support member.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.